Amine vaporization device and amine vaporization process

Abstract

The invention provides an amine vaporization device and an amine vaporization process, and particularly relates to the technical field of isocyanate synthesis. The amine vaporization device is an amine vaporization tower; a feeding hole is formed in the bottom of the amine vaporizing tower and is used for guiding amine liquid into the amine vaporizing tower; a discharge hole is formed in the top of the amine vaporizing tower and is used for guiding amine steam to be discharged out of the amine vaporizing tower; a leftover material collecting tank is arranged at the bottom of the amine vaporizing tower and is used for collecting leftover materials settled by the amine vaporizing tower; an overflow groove is formed above the feeding hole; a circulating tank is arranged at the bottom of the overflow groove; a porous baffle plate is arranged above the leftover material collecting tank and below the feeding hole; a liquid conveying device is arranged in the amine vaporizing tower; the liquid conveying device comprises a spiral channel, and a spiral baffle is arranged outside the spiral channel and used for guiding amine liquid to flow and enhancing turbulence.

Description

Technical Field

[0001] The invention relates to the technical field of isocyanate synthesis, in particular to an amine vaporization device and an amine vaporization process. Background Art

[0002] Isocyanates, as a key class of organic compounds, play a vital role in the field of polyurethane resin synthesis. At present, phosgenation is the dominant technology for industrial production of isocyanates, which is achieved by the reaction of amines or amine hydrochlorides with phosgene (phosgene).

[0003] Although the gas phase phosgenation method has higher product yields and lower equipment investment and solvent usage than the liquid phase phosgenation method in the synthesis of aliphatic and aromatic isocyanates, it faces separation problems when dealing with certain isocyanates, especially toluene diisocyanate. The isomers of these isocyanates are difficult to separate due to their similar boiling points, resulting in a large amount of impurities in the raw materials, such as waste and tar. These impurities not only affect the purity of the product, but may also have a negative impact on the color, quality and performance of the product. At the same time, these isocyanates are also heat-sensitive materials. During the high-temperature heating process of vaporization, impurities such as phenazine and hydrogenated azo carried by amines are easily polymerized to generate waste and tar substances. Therefore, in order to improve the quality and purity of isocyanates, additional purification and separation measures must be taken during the production process to ensure that these impurities are effectively removed to avoid damage to product performance.

[0004] In the amine vaporization process, falling film evaporation technology can usually only achieve a vaporization rate of 10%-15% due to the limitation of its heat transfer temperature difference. Although electric heaters can provide higher temperatures, there are hot spot problems, which may cause coking of the heating network, affect heating efficiency and damage the equipment. In the process of improving the vaporization efficiency of falling film evaporation to reduce gas-liquid entrainment and the generation of heaps, increasing the temperature or vaporization rate often leads to energy waste and an increase in amine heaps, and there is a trade-off between the two. The discharge of amine heaps is usually carried out in the intermittent process of isocyanate production. The discharge under abnormal conditions may carry a large amount of raw material loss, reducing the raw material conversion rate and product yield.

[0005] Therefore, when optimizing the amine vaporization process, it is necessary to balance the relationship between improving the gasification efficiency and reducing energy consumption and the generation of waste materials to improve the efficiency and economy of the production process. This may include improving the existing process or exploring new vaporization technologies to optimize energy use and reduce raw material losses while ensuring product quality.

[0006] The gas phase phosgenation process may also produce some byproducts that are difficult to completely remove, such as hydrogenated azo, oxidized azo and azobenzene compounds, especially when a specific isomer ratio needs to be maintained. Excessive hydrogenation may generate ketoamines, which have similar physical properties to tar and are easily mixed into the downstream products of phosgenation, affecting the color and quality of the products. In order to solve these problems, effective measures need to be taken in the amine vaporization stage to separate and remove these impurities to avoid irreversible effects on the quality of downstream products and ensure the purity and performance of the final product.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] One of the purposes of the present invention is to provide an amine vaporization device, aiming to solve at least one of the above technical problems.

[0009] A second object of the present invention is to provide an amine vaporization process.

[0010] In order to solve the above-mentioned technical problems, the present invention particularly adopts the following technical solutions:

[0011] A first aspect of the present invention provides an amine vaporization device, wherein the amine vaporization device is an amine vaporization tower;

[0012] The bottom of the amine vaporization tower is provided with a feed port for guiding amine liquid to enter the interior of the amine vaporization tower; the top of the amine vaporization tower is provided with a discharge port for guiding amine gas to discharge the amine vaporization tower; the bottom of the amine vaporization tower is provided with a waste material collection tank for collecting waste materials settled in the amine vaporization tower; an overflow trough is provided above the feed port, and a circulation tank is provided at the bottom of the overflow trough; a porous baffle is provided above the waste material collection tank and below the feed port; and a liquid conveying device is provided inside the amine vaporization tower.

[0013] Furthermore, the liquid conveying device is arranged cocentrically with the amine vaporization tower.

[0014] Preferably, the liquid conveying device comprises a spiral channel, and a spiral baffle is arranged outside the spiral channel to guide the flow of the amine liquid and enhance turbulence.

[0015] Preferably, the diameter of the spiral channel increases step by step from the bottom to the top to meet the requirements of vaporization and turbulence of the liquid during the transmission process.

[0016] Furthermore, the bottom diameter of the spiral channel is 1 / 5 to 1 / 3 of the diameter of the outer cylinder of the liquid conveying device.

[0017] The top diameter of the spiral channel is 1 / 2 to 2 / 3 of the diameter of the outer cylinder of the liquid conveying device.

[0018] Preferably, the diameter of the spiral channel increases step by step from the bottom to the top by 1.05 to 1.15 times.

[0019] Furthermore, the outer diameter of the porous baffle is the same as the inner diameter of the amine vaporization tower.

[0020] Preferably, a plurality of holes are evenly distributed in the peripheral edge region of the porous baffle, and no hole is arranged at the center position, and the holes are used for the passage of the scraps and the scraps are enriched in the scraps collection tank.

[0021] Furthermore, the diameter of the holes is 1 / 10 to 1 / 3 of the outer diameter of the porous baffle.

[0022] The distance between the center of the hole and the porous baffle is 3 to 10 times the diameter of the hole.

[0023] Furthermore, an overflow plate is provided at the portion where the overflow tank is connected to the amine vaporization tower to perform preliminary screening on the overflow liquid to prevent the waste material from entering the discharge port.

[0024] Preferably, the circulation tank is communicated with the feed port.

[0025] Preferably, the feed inlet is also provided with an amine preheater to preheat the amine liquid before entering the amine vaporization tower.

[0026] Furthermore, a heating jacket is provided on the outside of the amine vaporization tower and at a portion corresponding to the liquid conveying device, and a heating medium flows inside the heating jacket to heat the amine vaporization tower.

[0027] Preferably, the heating medium includes thermal oil or molten salt;

[0028] Preferably, the temperature of the heating medium is 330-350°C.

[0029] Preferably, the discharge port is provided with a condensate collecting tank, which is connected to the amine vaporizing tower and is used for returning the amine liquid in the amine vapor to the amine vaporizing tower.

[0030] The second aspect of the present invention provides an amine vaporization process, which is carried out using the amine vaporization device described in the first aspect. First, amine liquid enters the amine vaporization tower through a feed port, and the amine liquid is vaporized step by step through a liquid conveying device inside the amine vaporization tower. The waste material is collected above the porous baffle along the wall of the amine vaporization tower by sedimentation, and then enters a waste material collection tank; the amine liquid continuously overflows into a circulation tank through an overflow tank; the amine liquid in the circulation tank is mixed with the raw material amine and then re-enters the feed port to form a cycle; the obtained amine vapor enters the next process through a discharge port.

[0031] Furthermore, the amine in the amine solution includes at least one of aromatic amines, aliphatic amines, cyclic amines, polymer amines and special amines.

[0032] Preferably, the aromatic amine includes at least one of methylenediphenylenediamine, toluenediamine, xylylenediamine, diaminobenzene, 2,6-xylidine and 1,5-naphthylenediamine.

[0033] Preferably, the aliphatic amine includes at least one of 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 2,2-dimethyl-1,5-diaminopentane, 2-methyl-1,5-pentanediamine, 2,4,4-trimethyl-1,6-diaminohexane and 2,2,4-trimethyl-1,6-diaminohexane.

[0034] Preferably, the cyclic amine includes at least one of 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, 2,4-diamino-1-methylcyclohexane, 2,6-diamino-1-methylcyclohexane, 1-amino-1-methyl-4(3)-aminomethylcyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, 4,4'-diaminodicyclohexyl-methane, 2,4'-diaminodicyclohexyl-methane, triaminocyclohexane tris(aminomethyl)cyclohexane and triamino-methylcyclohexane.

[0035] Preferably, the polymeric amine includes at least one of polymethylene polyphenylene polyamines, methylene diphenylene polyamines, polyether amines and polyester amines.

[0036] Preferably, the special amine includes isophorone diamine and / or 3,3'-dichloro-4,4'-diaminodiphenylmethane. Further, the liquid conveying device realizes separation of amine vapor and heels by rotation.

[0037] Preferably, the rotation speed is 300-3000 rpm.

[0038] Preferably, the temperature of the amine solution at the feed inlet is 150-320°C.

[0039] Preferably, the amine vaporization pressure is 70-80 kPa.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] The amine vaporization device provided by the present invention conveys the amine liquid from bottom to top through a liquid conveying device, and increases the effective contact area between the amine material and the heat exchanger by means of upward centrifugal force. This innovative method not only improves the vaporization efficiency of the amine, but also shows particularly obvious advantages for treating amines with a wide variety of isomers and a high rate of scrap raw materials, such as toluene diisocyanate. The amine vaporization tower is provided with a scrap collection tank at the bottom to collect scraps settled in the tower. In addition, an overflow trough and a circulation tank are specially designed in the amine vaporization tower, as well as a porous baffle located above the scrap collection tank and below the feed port. These structures work together to collect and circulate the pure amine liquid through overflow, which not only improves the anti-blocking property of the amine vaporization tank, but also ensures the continuity and stability of the amine vaporization process. The liquid conveying device further ensures the uniform distribution and effective vaporization of the amine liquid in the tower. By enriching scraps in the dead zone of the device, effective discharge of scraps is achieved, and equipment blockage and unstable operation caused by scrap accumulation are avoided. The combination of these technologies not only improves the efficiency of amine vaporization, but also solves the problem of amine tailings discharge, ensuring the long-term stable operation of the amine vaporization device, which has important practical significance for industrial production.

[0042] The amine vaporization process provided by the present invention realizes efficient vaporization of amine liquid and effective management of waste materials in view of the advantages brought by the above-mentioned amine vaporization device. The amine liquid is ensured to be vaporized step by step in the amine vaporization tower through a liquid conveying device, so that the amine liquid is evenly distributed in the tower, thereby maximizing the vaporization efficiency and providing a high-quality amine source for subsequent chemical reactions. The amine vaporization process not only improves production efficiency, but also reduces energy consumption and raw material waste, improves the economic benefits of the entire production process, and reduces the production cost of isocyanate. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 A schematic diagram of the structure of the amine vaporization device provided by the present invention;

[0045] Figure 2 It is a structural schematic diagram of a liquid conveying device;

[0046] Figure 3 is a schematic diagram of the structure of a porous baffle;

[0047] Figure 4 This is a schematic diagram of the structure of the amine vaporization device provided in Example 1.

[0048] Explanation of the main component symbols: 10-feed port; 20-discharge port; 22-demister; 24-condensate collection tank; 30-feed collection tank; 40-overflow trough; 50-circulation tank; 60-porous baffle; 62-hole; 70-liquid conveying device; 72-spiral baffle; 80-heating jacket; 82-heat source inlet; 84-heat source outlet. DETAILED DESCRIPTION

[0049] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in combination with the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, but not all of the embodiments. The components of the embodiment of the present invention can be arranged and designed in various different configurations.

[0050] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0051] A first aspect of the present invention provides an amine vaporization device, such as Figure 1 As shown, the amine vaporization device is an amine vaporization tower;

[0052] A feed port 10 is provided at the bottom of the amine vaporization tower for guiding amine liquid into the interior of the amine vaporization tower; a discharge port 20 is provided at the top of the amine vaporization tower for guiding amine gas to discharge the amine vaporization tower through the feed port 10; a waste material collecting tank 30 is provided at the bottom of the amine vaporization tower for collecting waste materials settled in the amine vaporization tower; an overflow trough 40 is provided above the feed port 10, and a circulation tank 50 is provided at the bottom of the overflow trough 40; a porous baffle 60 is provided above the waste material collecting tank 30 and below the feed port 10; a liquid conveying device 70 is provided inside the amine vaporization tower.

[0053] The amine vaporization device provided by the present invention transports the amine liquid from bottom to top through the liquid conveying device 70, and increases the effective contact area between the amine material and the heat exchanger by means of the upward centrifugal force. This innovative method not only improves the vaporization efficiency of the amine, but also shows particularly obvious advantages for treating amines with a wide variety of isomers and a high rate of scrap raw materials, such as toluene diisocyanate. The amine vaporization tower is provided with a scrap collection tank 30 at the bottom for collecting scraps settled in the tower. In addition, the amine vaporization tower is also specially designed with an overflow tank 40 and a circulation tank 50, as well as a porous baffle 60 located above the scrap collection tank 30 and below the feed port 10. These structures work together to collect and circulate the pure amine liquid through overflow, which not only improves the anti-blocking property of the amine vaporization tank, but also ensures the continuity and stability of the amine vaporization process. The liquid conveying device 70 further ensures the uniform distribution and effective vaporization of the amine liquid in the tower. By enriching the waste materials in the dead zone of the device, the waste materials are effectively discharged, avoiding equipment blockage and unstable operation caused by the accumulation of waste materials. The combination of these technologies not only improves the amine vaporization efficiency, but also solves the problem of amine waste material discharge, ensuring the long-term stable operation of the amine vaporization device, which has important practical significance for industrial production.

[0054] In one embodiment of the present invention, the liquid conveying device 70 is disposed cocentrically with the amine vaporization tower to ensure uniform distribution and effective flow of the amine liquid in the amine vaporization tower.

[0055] In one embodiment of the present invention, the liquid delivery device 70 comprises a spiral channel, such as Figure 2 As shown, spiral baffles 72 are arranged in a spiral shape on the outside of the spiral channel. These spiral baffles 72 allow the liquid to transfer the material input from the feed inlet 10 upward along a spiral path.

[0056] Preferably, the diameter of the spiral channel increases step by step from the bottom to the top to meet the vaporization and turbulence requirements of the liquid during the transmission process. As the spiral diameter increases, the centrifugal force received by the liquid also increases, thereby promoting turbulence and heat exchange between the liquid and the heating wall, and improving the vaporization efficiency. This spiral channel design can increase the heat exchange efficiency to 20-25%, which is a significant technological advancement compared to the 10-15% heat exchange efficiency of traditional heat-sensitive materials.

[0057] Furthermore, the bottom diameter of the spiral channel is 1 / 5 to 1 / 3 of the outer diameter of the liquid conveying device 70, and specifically can be 1 / 5, 1 / 4 or 1 / 3. The bottom diameter within the above range is helpful to screen and separate the waste materials contained in the feeding stage and above the porous baffle 60 to prevent them from being conveyed to the evaporation area. At the same time, the bottom diameter can also effectively generate centrifugal force to push the material to the surroundings, so that it moves upward along the spiral baffle 72 in the spiral channel.

[0058] In some embodiments of the present invention, the top diameter of the spiral channel is 1 / 2 to 2 / 3 of the diameter of the outer cylinder of the liquid conveying device 70, and specifically can be 1 / 2, 3 / 5, 4 / 7, 5 / 8, 7 / 11 or 2 / 3.

[0059] Preferably, the diameter of the spiral channel increases step by step from the bottom to the top by 1.05 to 1.15 times, and the specific enlargement ratio can be 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14 or 1.15. This progressive diameter increase design helps to gradually increase the centrifugal force of the liquid during the liquid transmission process, thereby promoting effective heat exchange and vaporization between the liquid and the heating wall. At the same time, this design also helps to achieve uniform distribution of the liquid during the rising process of the spiral channel, avoid local overheating or poor flow, and ensure the efficiency and stability of the entire liquid transmission and vaporization process. In the process of the liquid passing through the spiral channel, the amine liquid is continuously heated and vaporized, and rises to the position of the discharge port 20; other substances such as the foot material are still in a liquid state. As the spiral diameter increases, the centrifugal force becomes larger and larger, and then it is thrown out of the spiral channel and enriched downstream along the amine vaporization tower wall.

[0060] In order to ensure that the liquid conveying device 70 operates efficiently in the amine vaporization tower, the present invention is equipped with a motor at the top of the amine vaporization tower. The motor provides the necessary power for the liquid conveying device 70 to drive the liquid to be transported upward along the spiral channel. The installation position of the motor at the top of the amine vaporization tower helps to reduce the complexity of the transmission system and can directly convert the output of the motor into the mechanical movement of the liquid conveying device 70. In addition, the top-mounted motor can also reduce the occupation of the internal space of the tower, making the internal structure of the amine vaporization tower more compact, and also facilitates the maintenance and repair of the motor.

[0061] Furthermore, the outer diameter of the porous baffle 60 is the same as the inner diameter of the amine vaporization tower, so that the porous baffle 60 fits tightly against the tower wall, ensuring that the liquid is in full contact with the tower wall during the rising process, thereby improving the heat exchange efficiency.

[0062] In addition, the consistency of the outer diameter of the porous baffle 60 with the inner diameter of the amine vaporizer column also helps to simplify the manufacturing and installation process of the device, because it allows the baffle to be directly installed in the column as an integral component without additional adjustment or adaptation. This design also facilitates the maintenance and cleaning of the baffle, because the close fit of the baffle and the column wall reduces the accumulation of materials between the baffle and the column wall.

[0063] Preferably, if Figure 3As shown, a plurality of holes 62 are evenly distributed in the peripheral edge area of ​​the porous baffle 60, and no hole 62 is set at the center of the circle. The hole 62 is used for the passage of the scraps and is enriched in the scrap collection tank 30. The design of the porous baffle 60 utilizes the principle of centrifugal force to achieve effective separation and collection of the scraps, while avoiding hollow vortices that may be generated during the high-speed rotation of the scraps, which may interfere with the measurement of the viscometer and affect its accuracy.

[0064] Specifically, the porous baffle 60 allows the scraps to sink smoothly under the action of centrifugal force and enter the scrap collection tank 30 through the hole 62, thereby realizing continuous collection of the scraps; at the same time, the hole 62 is not set at the center position to prevent the liquid conveying device 70 from forming a hollow vortex when rotating at high speed, disrupting the flow of the liquid and causing inaccurate viscometer readings.

[0065] In one embodiment of the present invention, a viscometer is provided in the heap material collection tank 30 for reading the viscosity of the heap material in the heap material collection tank 30. By regularly monitoring the changes in the viscometer, the operator can accurately determine when to discharge the heap material, thereby achieving regular cleaning of the heap material in the heap material collection tank 30. This regular discharge mechanism helps maintain the stability and efficiency of the entire system and prevents the performance of the amine vaporizer from being affected by the accumulation of heap material.

[0066] Furthermore, the diameter of the hole 62 is 1 / 10 to 1 / 3 of the outer diameter of the porous baffle plate 60, and can be specifically 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4 or 1 / 3 of the outer diameter of the porous baffle plate 60, thereby ensuring a reasonable distribution of the holes 62 on the baffle plate, which can not only achieve effective sinking of the scraps, but also avoid structural strength problems caused by excessively large holes 62.

[0067] The distance between the center of the hole 62 and the porous baffle 60 is 3 to 10 times the diameter of the hole 62, specifically 3, 4, 5, 6, 7, 8, 9 or 10 times, to ensure that the hole 62 can receive the waste material flowing down the wall and will not produce adverse fluid dynamics such as hollow vortex due to excessive centrifugal force. This distance setting helps maintain the stability of fluid flow and prevent splashing or leakage that may occur during high-speed rotation.

[0068] Furthermore, the portion where the overflow tank 40 is connected to the amine vaporization tower is provided with an overflow plate to preliminarily screen the overflow liquid and prevent the waste material from entering the discharge port 20. In the process of the liquid conveying device 70 realizing the upward vaporization by rotation, the liquid will flow downward along the wall and pass through the overflow tank 40. Since the overflow tank 40 is close to the wall on three sides, the waste material flowing down on one side will be flushed into the circulation tank 50 during the overflow process. The setting of the overflow plate can effectively prevent the waste material from being entrained by the overflow, ensuring that the waste material will not enter the circulation tank 50 by mistake, thereby maintaining the purity of the circulating liquid. Even if a small amount of waste material enters the overflow tank 40, since the feeding position of the circulating amine and the fresh amine is close to the porous baffle 60 after preheating, the amine liquid will be further separated under the action of centrifugal force, avoiding the waste material from being directly brought into the vaporization process. This design ensures that the waste material enters the waste material collection tank 30 mainly by wall flow, rather than through the circulation path.

[0069] The main function of the overflow tank 40 is to introduce the amine liquid with a small amount of scrap or no scrap into the circulation tank 50 by overflow, so as to provide the circulation volume required for amine vaporization. With the continuous replenishment of fresh amine and circulating amine, the overflow tank 40 realizes continuous overflow to ensure the continuous and stable operation of the entire device. The overflow is realized based on the entire amine scrap collection tank 30 being in a full liquid state, which not only ensures that the liquid conveying device 70 can be completely immersed in the liquid and effectively convey the liquid by using the baffle, but also ensures that the amine liquid can continuously and stably flow into the circulation tank 50 through the weir.

[0070] The design of the circulation tank 50 allows the amine liquid after centrifugal screening, that is, the amine flow containing no or little heavy components, to enter the circulation tank 50 through overflow for circulation evaporation. The feeding position of the circulating amine is designed to be below the liquid level, above the porous baffle 60, and is transported to the top by the centripetal force provided by the spiral baffle 72 of the liquid conveying device 70.

[0071] As the radius increases, when the centrifugal force is greater than the centripetal force, the amine liquid will impact the amine vaporization tower wall and be heated and vaporized. The advantage of this design is that the overflow liquid can ensure that the proportion of heavy components in the amine feed is reduced, and the heavy components are initially screened through gravity sedimentation to prevent too many heavy components from entering the circulation and being heated, thereby avoiding the problems of affecting the vaporization efficiency and abnormal temperature rise of the device, and avoiding the vicious cycle of accelerating the rate of heel material generation. In addition, this design also effectively improves the detectability of heel material discharge and provides operators with more accurate heel material management information.

[0072] Preferably, the circulation tank 50 is connected to the feed port 10 for circulating the collected amine liquid.

[0073] Preferably, the feed port 10 is also provided with an amine preheater to preheat the amine liquid before entering the amine vaporization tower. The temperature of the amine liquid is increased by preheating, thereby reducing the burden of the internal heating system of the amine vaporization tower and improving the overall heat exchange efficiency.

[0074] Furthermore, a heating jacket 80 is provided outside the amine vaporization tower and at a portion corresponding to the liquid conveying device 70 , and a heating medium flows inside the heating jacket 80 to heat the amine vaporization tower.

[0075] In the specific implementation process, a variety of heat sources can be considered to be used in the heating jacket 80, such as steam, hot water or electric heater, etc. The flow direction of the heat source in the heating jacket 80 is from the heat source inlet 82 into the heating jacket 80 and out of the heating jacket 80 from the heat source outlet 84.

[0076] Preferably, the discharge port 20 is provided with a condensate collecting tank 24, and the condensate collecting tank 24 is connected to the amine vaporizing tower and is used for returning the amine liquid in the amine vapor to the amine vaporizing tower.

[0077] In some embodiments of the present invention, the discharge port 20 is provided with a demister 22, and the vaporized amine enters the subsequent amine superheater through the demister 22 to increase the temperature of the amine vapor to exceed its bubble point temperature by 15 to 50° C., thereby ensuring that the amine vapor remains in a stable gaseous state during subsequent transmission and application, and avoiding condensation or formation of droplets in the pipeline or equipment. A condensate collection tank 24 is provided at the lower part of the discharge port 20, and the condensate collection tank 24 is connected to the inside of the amine vaporization tower. The condensate can be returned to the amine vaporization tower through the connection management for re-vaporization. In order to facilitate the control of the condensate, a valve can be provided on the connecting pipeline.

[0078] The second aspect of the present invention provides an amine vaporization process, which is carried out using the amine vaporization device described in the first aspect. First, amine liquid enters the amine vaporization tower through the feed port 10, and the amine liquid is vaporized step by step through the liquid conveying device 70 inside the amine vaporization tower. The waste material is collected above the porous baffle 60 along the wall of the amine vaporization tower by sedimentation, and then enters the waste material collection tank 30; the amine liquid continuously overflows into the circulation tank 50 through the overflow tank 40; the amine liquid in the circulation tank 50 is mixed with the raw amine and then re-enters the feed port 10 to form a cycle; the obtained amine vapor enters the next process through the discharge port 20.

[0079] The amine vaporization process provided by the present invention realizes efficient vaporization of amine liquid and effective management of waste materials in view of the advantages brought by the above-mentioned amine vaporization device. The amine liquid is ensured to be vaporized step by step in the amine vaporization tower through the liquid conveying device 70, so that the amine liquid is evenly distributed in the tower, thereby maximizing the vaporization efficiency and providing a high-quality amine source for subsequent chemical reactions. The amine vaporization process not only improves production efficiency, but also reduces energy consumption and raw material waste, improves the economic benefits of the entire production process, and reduces the production cost of isocyanate.

[0080] Furthermore, the amine in the amine solution includes at least one of aromatic amines, aliphatic amines, cyclic amines, polymer amines and special amines.

[0081] Preferably, the aromatic amine includes at least one of methylenediphenylenediamine, toluenediamine, xylylenediamine, diaminobenzene, 2,6-xylidine and 1,5-naphthylenediamine.

[0082] Preferably, the aliphatic amine includes at least one of 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 2,2-dimethyl-1,5-diaminopentane, 2-methyl-1,5-pentanediamine, 2,4,4-trimethyl-1,6-diaminohexane and 2,2,4-trimethyl-1,6-diaminohexane.

[0083] Preferably, the cyclic amine includes at least one of 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, 2,4-diamino-1-methylcyclohexane, 2,6-diamino-1-methylcyclohexane, 1-amino-1-methyl-4(3)-aminomethylcyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, 4,4'-diaminodicyclohexyl-methane, 2,4'-diaminodicyclohexyl-methane, triaminocyclohexane tris(aminomethyl)cyclohexane and triamino-methylcyclohexane.

[0084] Preferably, the polymeric amine includes at least one of polymethylene polyphenylene polyamines, methylene diphenylene polyamines, polyether amines and polyester amines.

[0085] Preferably, the special amine includes isophorone diamine and / or 3,3'-dichloro-4,4'-diaminodiphenylmethane. Further, the liquid conveying device 70 realizes separation of amine vapor and heap by rotation.

[0086] Preferably, the rotation speed is 300-3000 rpm.

[0087] Typically but not limiting, the rotation speed can be, for example, 300rpm, 400rpm, 500rpm, 600rpm, 700rpm, 800rpm, 900rpm, 1000rpm, 1200rpm, 1500rpm, 1800rpm, 2100rpm, 2400rpm, 2700rpm or 3000rpm, or any value within the range of 300rpm to 3000rpm.

[0088] Preferably, the temperature of the amine solution at the feed port 10 is 150-320°C.

[0089] Typically but not limiting, the temperature of the amine solution at the feed port 10 can be, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C or 320°C, or any value within the range of 150°C to 320°C.

[0090] Preferably, the temperature of the amine vapor at the discharge port 20 is 15-50° C. higher than the amine bubble point temperature.

[0091] Typically but not limiting, the amine vapor temperature at the discharge port 20 can be higher than the bubble point temperature of the amine, for example, it can be 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C higher, or it can be any value within the range of 15°C to 50°C higher than the bubble point temperature of the amine.

[0092] The amine vaporization device and / or amine vaporization process provided by the present invention can be used for the synthesis of isocyanate.

[0093] Typically, but not limiting, isocyanates include toluene diisocyanate (TDI), methyl isocyanate, ethyl isocyanate, propyl isocyanate, phenyl isocyanate, cyclohexyl isocyanate, 1,4-butanediisocyanate, 1,5-pentanediisocyanate (PDI), 1,6-hexanediisocyanate (HDI), cyclohexanedimethylene diisocyanate (HXDI), 1,5-diisocyanato-2-methylpentane, 1,4-diisocyanatocyclohexane (CHDI), isophorone diisocyanate (IPDI), meta-xylylene diisocyanate (XDI), 4,4'-dicyclohexylmethane diisocyanate (H12MDI) , toluene diisocyanate (TDI), paraphenylene diisocyanate (PPDI), 1,5-naphthalene diisocyanate (NDI), methylcyclohexane diisocyanate (HTDI), trimethylhexane diisocyanate (TMDI), tetramethyl meta-xylylene diisocyanate (TMXDI), dimethyl biphenyl diisocyanate (TODI), norbornane dimethylene isocyanate (NBDI), 1,8-diisocyanato-4-isocyanatomethyl octane, nonane triisocyanate, 2-tetrahydrofuran isocyanate, naphthalene 1,5-diisocyanate (1,5-NDI), cyclohexane 1,3-diisocyanate or cyclohexane 1,4-diisocyanate.

[0094] In the following, some embodiments of the present invention are described in detail in conjunction with the examples. In the absence of conflict, the following examples and features in the examples can be combined with each other. The raw materials in the following examples and comparative examples are purchased from the market unless otherwise specified.

[0095] Example 1

[0096] This embodiment provides an amine vaporization device, such as Figure 4 As shown, the amine vaporization device is an amine vaporization tower, a feed port 10 is provided at the bottom of the amine vaporization tower, a discharge port 20 is provided at the top, a waste material collecting tank 30 is provided at the bottom, an overflow trough 40 is provided above the feed port 10, and a circulation tank 50 is provided at the bottom of the overflow trough 40; a porous baffle 60 is provided above the waste material collecting tank 30 and below the feed port 10; a liquid conveying device 70 is provided inside the amine vaporization tower.

[0097] The liquid conveying device 70 is arranged coaxially with the amine vaporizing tower, and a spiral channel is arranged inside, and the diameter of the spiral channel increases step by step from the bottom to the top. The top of the amine vaporizing tower is equipped with a motor, which is connected to the liquid conveying device 70 to provide power for the liquid conveying device 70 to drive the liquid to be transported upward along the spiral channel.

[0098] A porous baffle 60 is provided below the feed port 10 of the amine vaporization tower. The porous baffle 60 is arranged in close contact with the tower wall of the amine vaporization tower to collect the waste material flowing down from the tower wall. A plurality of holes 62 are evenly distributed in the peripheral edge area of ​​the porous baffle 60, and no hole 62 is provided at the center of the circle. The holes 62 are used for the waste material to pass through and be enriched in the waste material collection tank 30.

[0099] The materials on the tower wall enter the scrap collection tank 30 through the porous baffle 60 . The scrap collection tank 30 is provided with a viscometer for reading the viscosity of the scrap in the scrap collection tank 30 .

[0100] An overflow trough 40 is arranged above the feed port 10 , and an overflow plate is arranged at the portion where the overflow trough 40 is connected to the tower wall. A circulation tank 50 is connected to the rear of the overflow trough 40 to collect the liquid in the overflow trough 40 .

[0101] The circulation tank 50 is connected to the feed port 10 through a pipeline, and a circulation pump is provided on the pipeline to provide power for the flow of the liquid in the circulation tank 50. The circulating amine liquid merges with the original amine liquid at the front section of the amine preheater and enters the feed port 10 after being preheated by the amine preheater.

[0102] A heating jacket 80 is provided outside the amine vaporization tower and at a portion corresponding to the liquid conveying device 70 . A heating medium flows inside the heating jacket 80 , enters the heating jacket 80 from a heat source inlet 82 , and exits the heating jacket 80 from a heat source outlet 84 , thereby heating the amine vaporization tower.

[0103] The discharge port 20 is provided with a demister 22 and a condensate collecting tank 24, the condensate collecting tank 24 is connected to the amine vaporizing tower, and is used to return the amine liquid in the amine vapor to the amine vaporizing tower. The rear end of the demister 22 is connected to an amine superheater, which is used to heat the amine vapor.

[0104] Example 2

[0105] This embodiment provides a vaporization process of toluenediamine, which is carried out in the amine vaporization device provided in Example 1. The specific process steps are as follows:

[0106] 1. Toluenediamine is preheated in an amine preheater to 290°C and enters the amine vaporizer through the feed port. The pressure in the amine vaporizer is 70 kPa, and the temperature of the heat source in the heating jacket is 340°C. The heated toluenediamine runs upward through the liquid conveying device. The amine vapor temperature at the discharge port 20 is 330°C, and the speed of the liquid conveying device is set to 500 rpm.

[0107] 2. The screw speed, tailings discharge time, tailings concentration and amine vaporization rate detected during the process are recorded in Table 1.

[0108] Example 3

[0109] This embodiment provides a vaporization process of toluene diamine. The difference from Embodiment 2 is that the rotation speed of the liquid conveying device is set to 1000 rpm. The remaining raw materials and steps are the same as those in Embodiment 2 and will not be repeated here.

[0110] Example 4

[0111] This embodiment provides a vaporization process of toluene diamine. The difference from Embodiment 2 is that the rotation speed of the liquid conveying device is set to 1500 rpm. The remaining raw materials and steps are the same as those in Embodiment 2 and will not be repeated here.

[0112] Comparative Example 1

[0113] This comparative example provides a toluenediamine falling film vaporization process, wherein toluenediamine is preheated to 290°C and pumped into a falling film evaporator for vaporization, and a common shell-and-tube heat exchanger is selected for the falling film evaporator. The vaporization heat source is heated by 340°C heat transfer oil, and the amine circulation amount is constant. The heat transfer temperature difference is controlled by controlling the amount of heat transfer oil to ensure the amine vaporization rate; when the heat transfer temperature difference is consistent with the embodiment, which is 15°C, the amine vaporization rate can only reach 10%, and the waste rate, waste concentration, and discharge times in the process are recorded in Table 1.

[0114] Comparative Example 2

[0115] This comparative example provides a toluenediamine falling film vaporization process, wherein toluenediamine is preheated to 290°C and pumped into a falling film evaporator for vaporization, and a common shell-and-tube heat exchanger is selected for the falling film evaporator. The vaporization heat source is heated by 340°C heat transfer oil, and the amine circulation amount is constant. The heat transfer temperature difference is controlled by controlling the amount of heat transfer oil to ensure the amine vaporization rate; when the heat transfer temperature difference is 18°C, the amine vaporization rate is increased to 15%, and the waste rate, waste concentration, and discharge times in the process are recorded in Table 1.

[0116] Wherein, amine vaporization rate = gas phase amine flow rate entering reactor / liquid phase amine flow rate entering amine vaporization device*100%.

[0117] Table 1

[0118]

[0119] The discharge waste concentration in Table 1 is a fixed value, which refers to the minimum value that will affect the temperature and pressure changes of the amine vaporization device. Because the waste rate in the circulating vaporization liquid of the present invention is low and constant, the temperature and pressure of the vaporization device are less affected. The discharge waste concentration is an online detection reading, which refers to the waste ratio in the waste collection tank 30.

[0120] It can be seen from Table 1 that the waste material rate generated by the amine vaporization device provided by the present invention is almost the same as that generated by the ordinary falling film vaporization device. The waste material rate generated by the system is calculated as follows: (the absolute amount of waste materials contained in the waste materials discharged each year - the absolute amount of waste materials contained in the amine raw material feed) / the annual amine raw material consumption.

[0121] In the specific amine vaporization process, when the temperature of the waste tank rises to 317℃, it exceeds the normal fluctuation range (i.e. the interval of relatively slow temperature growth) and the growth rate increases significantly with the increase of time, and the time used for each 1℃ increase decreases, the waste concentration corresponding to 317℃ is detected to be 10%-12%. 317℃ is the critical point temperature value. As the emission standard, the discharge time and emission amount of waste can be controlled in real time, which effectively improves the operability and stability of the amine vaporization device. The waste concentration corresponding to 312-315℃ fluctuates between 0.5%-2%, which is the normal waste rate fluctuation range.

[0122] The concentration of the discharged waste materials in Example 2-4 is large, the number of discharges is small, and the discharge amount of the amine liquid containing the waste materials will be small; the energy consumption of the amine liquid containing the waste materials after distillation recovery in the later stage will also be reduced, which greatly improves the post-processing efficiency of the amine waste materials and improves the benefits.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An amine vaporization device, characterized in that: The amine vaporization device is an amine vaporization tower; The bottom of the amine vaporization tower is provided with a feed port for guiding the amine liquid to enter the interior of the amine vaporization tower; the top of the amine vaporization tower is provided with a discharge port for guiding the amine vapor to discharge the amine vaporization tower; the bottom of the amine vaporization tower is provided with a waste material collection tank for collecting waste materials settled in the amine vaporization tower; An overflow trough is arranged above the feed port, and a circulation tank is arranged at the bottom of the overflow trough; a porous baffle is arranged above the scrap material collecting tank and below the feed port; a liquid conveying device is arranged inside the amine vaporization tower; The liquid conveying device comprises a spiral channel, and a spiral baffle is arranged outside the spiral channel to guide the flow of the amine liquid and enhance turbulence.

2. The amine vaporization device according to claim 1, characterized in that: The liquid conveying device is arranged cocentrically with the amine vaporizing tower; Preferably, the diameter of the spiral channel increases step by step from the bottom to the top to meet the requirements of vaporization and turbulence of the liquid during the transmission process.

3. The amine vaporization device according to claim 2, characterized in that: The bottom diameter of the spiral channel is 1 / 5 to 1 / 3 of the diameter of the outer cylinder of the liquid conveying device; The top diameter of the spiral channel is 1 / 2 to 2 / 3 of the diameter of the outer cylinder of the liquid conveying device; Preferably, the diameter of the spiral channel increases step by step from the bottom to the top by 1.05 to 1.15 times.

4. The amine vaporization device according to claim 1, characterized in that: The outer diameter of the porous baffle is the same as the inner diameter of the amine vaporization tower; Preferably, a plurality of holes are evenly distributed in the peripheral edge region of the porous baffle, and no hole is arranged at the center position, and the holes are used for the passage of the scraps and the scraps are enriched in the scraps collection tank.

5. The amine vaporization device according to claim 4, characterized in that: The diameter of the hole is 1 / 10 to 1 / 3 of the outer diameter of the porous baffle; The distance between the center of the hole and the porous baffle is 3 to 10 times the diameter of the hole.

6. The amine vaporization device according to claim 1, characterized in that: The portion where the overflow tank is connected to the amine vaporization tower is provided with an overflow plate to preliminarily screen the overflow liquid to prevent the waste material from entering the discharge port; Preferably, the circulation tank is connected to the feed port; Preferably, the feed inlet is also provided with an amine preheater to preheat the amine liquid before entering the amine vaporization tower.

7. The amine vaporization device according to any one of claims 1 to 6, characterized in that: A heating jacket is provided on the outside of the amine vaporization tower and at a portion corresponding to the liquid conveying device, and a heating medium flows inside the heating jacket to heat the amine vaporization tower; Preferably, the discharge port is provided with a condensate collecting tank, which is connected to the amine vaporizing tower and is used to return the amine liquid in the amine vapor to the amine vaporizing tower; Preferably, the heating medium includes thermal oil or molten salt; Preferably, the temperature of the heating medium is 330-350°C.

8. An amine vaporization process, characterized in that: The amine vaporization device according to any one of claims 1 to 7 is used, firstly, the amine liquid enters the amine vaporization tower through the feed port, the amine liquid is vaporized step by step through the liquid conveying device inside the amine vaporization tower, the bottom materials are collected above the porous baffle along the wall of the amine vaporization tower by sedimentation, and then enter the bottom material collection tank; the amine liquid continuously overflows into the circulation tank through the overflow tank; the amine liquid in the circulation tank is mixed with the raw material amine and then re-enters the feed port to form a cycle; The obtained amine gas enters the next process through the discharge port.

9. The amine vaporization process according to claim 8, characterized in that: The amine in the amine solution includes at least one of aromatic amines, aliphatic amines, cyclic amines, polymer amines and special amines; Preferably, the aromatic amine includes at least one of methylenediphenylenediamine, toluenediamine, xylylenediamine, diaminobenzene, 2,6-xylidine and 1,5-naphthylenediamine; Preferably, the aliphatic amine includes at least one of 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 2,2-dimethyl-1,5-diaminopentane, 2-methyl-1,5-pentanediamine, 2,4,4-trimethyl-1,6-diaminohexane and 2,2,4-trimethyl-1,6-diaminohexane; Preferably, the cyclic amine includes at least one of 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, 2,4-diamino-1-methylcyclohexane, 2,6-diamino-1-methylcyclohexane, 1-amino-1-methyl-4(3)-aminomethylcyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, 4,4'-diaminodicyclohexyl-methane, 2,4'-diaminodicyclohexyl-methane, triaminocyclohexane tris(aminomethyl)cyclohexane and triamino-methylcyclohexane; Preferably, the polymeric amine comprises at least one of polymethylene polyphenylene polyamines, methylene diphenylene polyamines, polyether amines and polyester amines; Preferably, the specialty amine comprises isophoronediamine and / or 3,3'-dichloro-4,4'-diaminodiphenylmethane.

10. The amine vaporization process according to claim 8, characterized in that: The liquid conveying device separates the amine vapor and the heels by rotating; Preferably, the rotation speed is 300-3000 rpm; Preferably, the amine liquid temperature at the feed port is 150-320°C; Preferably, the amine vaporization pressure is 70-80 kPa.

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